Power Management for a Graphics Processing Unit or Other Circuit

1. An integrated circuit comprising: a graphics processing unit (GPU); a power monitor coupled to the GPU and configured to generate a power measurement representing power consumed in the GPU; and a controller coupled to the power monitor and the GPU, wherein: the controller is configured to limit a first amount of time within a given frame time that the GPU is powered on to no more than a first limit amount, the first limit amount is determined at a current operating point of the GPU to reduce an error between a target power measurement and the power measurement generated by the power monitor, a frame time is a period of time elapsing for a display of one frame on a display device; and the controller is configured to control the current operating point of the GPU responsive to the first amount of time.

2. The integrated circuit as recited in claim 1 wherein the current operating point comprises an operating voltage and an operating frequency of the GPU.

3. The integrated circuit as recited in claim 1 wherein the controller is configured to: detect that the first amount of time is less than a first threshold; and reduce the current operating point responsive to detecting that the first amount of time is less than the first threshold.

4. The integrated circuit as recited in claim 3 wherein the controller is configured to: detect that the first amount of time is greater than a second threshold and that the first limit amount is at a maximum; and increase the current operating point responsive to detecting that the first amount of time is greater than the second threshold and that the first limit amount is at the maximum.

5. The integrated circuit as recited in claim 1 further comprising a second processor and a non-transitory computer accessible storage medium storing a plurality of instructions implementing at least a portion of the controller, wherein the second processor is configured to execute at least a portion of the plurality of instructions.

6. The integrated circuit as recited in claim 5 wherein a remaining portion of the controller is implemented in hardware circuitry.

7. The integrated circuit as recited in claim 1 wherein the controller is configured to power off the GPU in the given frame time in response to completion of a task even if the first limit amount has not been exhausted.

8. The integrated circuit as recited in claim 1 wherein the power monitor is configured to estimate the power measurement responsive to activity in the GPU.

9. The integrated circuit as recited in claim 1 wherein the power monitor is configured to measure the power consumption from a power supply to the GPU to determine the power measurement.

10. The integrated circuit as recited in claim 1 wherein the power monitor is configured to measure a current from a power supply to the GPU to determine the power measurement.

11. An integrated circuit comprising: a first processor; and a controller coupled to the first processor, wherein: the controller is configured to limit a first amount of time that the first processor is powered on at a current operating point within a given fixed time period to at most a first limit amount; the first limit amount is determined by the controller at the current operating point responsive to a target power measurement representing a target power consumption for the first processor and a present power measurement representing an actual power consumption of the first processor; the given fixed time period is one of a plurality of fixed time periods over which the first processor operates, wherein the first processor performs a task within each of the plurality of fixed time periods; and the controller is configured to control the current operating point of the first processor responsive to the first amount of time that the first processor is powered on within the given fixed time period.

12. The integrated circuit as recited in claim 11 further comprising a power monitor coupled to the first processor and configured to generate the present power measurement.

13. The integrated circuit as recited in claim 12 wherein the actual power consumption is an estimate generated by the power monitor.

14. The integrated circuit as recited in claim 12 wherein the actual power measurement is physically measured by the power monitor.

15. The integrated circuit as recited in claim 11 further comprising at least one temperature sensor configured to measure a temperature of the integrated circuit, wherein the controller is configured to generate the target power measurement responsive to the temperature.

16. A method comprising: determining, at a current operating point of a graphics processing unit (GPU), a first limit amount to reduce an error between a target power measurement and a power measurement generated by a power monitor that monitors to the GPU; limiting a first amount of time within a given frame time that the GPU is powered on to no more than the first limit amount, wherein a frame time is a period of time elapsing for a display of one frame on a display device; and controlling the current operating point of the GPU responsive to the first amount of time.

17. The method as recited in claim 16 wherein controlling the current operating point comprises reducing at least one of an operating voltage and an operating frequency to increase the first amount of time responsive to the first amount of time being less than a first threshold.

18. The method as recited in claim 16 wherein controlling the current operating point comprises increasing at least one of an operating voltage and an operating frequency to decrease the first amount of time responsive to detecting that the first amount of time is greater than a second threshold and that the first limit amount is at a maximum.

19. The method as recited in claim 16 further comprising powering off the GPU in the given frame time in response to completion of a task even if the first limit amount has not been exhausted.

20. The method as recited in claim 16 wherein the power measurement from the power monitor is an estimated power measurement.